The world's longest outdoor covered escalator system transports commuters through Hong Kong's hilly terrain.

Teeming with illegal goods and services, this towering maze of vice is also a popular tourist accommodation.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

An ancient city hidden in the heart of the Sierra Nevada mountains.

An unusual and beautiful form of mass transit serves the city's steepest neighborhoods.

The world's tallest palm trees look like the whimsical kind of plant you'd find in a Dr. Seuss story.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

Northern Ireland's Brobdingnagian stepping stones.

A palatial former bank building now houses what may be the poshest art venue (and former Tesco) in Belfast.

This Victorian-era public house has set the standard for pub-style elegance for over a hundred years.

It was once nicknamed "the most bombed hotel in Europe."

The first piece of public art dedicated to LGBT rights.

Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

The other side is actually green.

Founded as a refugee camp, now a popular tourist spot.

An important landmark in the history of algebraic logic.

An 80-year-old plane tree is devouring an iron bench at Ireland's oldest law school.

The Grand Lodge of Ireland is one of the oldest in the world, full of fantastical, elaborately themed rooms.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.